The Cosmic Infrared Background Experiment (CIBER): the Narrow Band Spectrometer

TL;DR

The CIBER narrow band spectrometer measures the Solar CaII Fraunhofer line in Zodiacal light to improve models of interplanetary dust and refine extragalactic background light estimates.

Contribution

It introduces a specialized near-infrared spectrometer with high sensitivity for rocket-based measurements of Zodiacal light using the CaII Fraunhofer line.

Findings

Laboratory characterization of the instrument

Successful flight performance data

Enhanced accuracy in Zodiacal brightness measurement

Abstract

We have developed a near-infrared spectrometer designed to measure the absolute intensity of the Solar 854.2 nm CaII Fraunhofer line, scattered by interplanetary dust, in the Zodiacal light spectrum. Based on the known equivalent line width in the Solar spectrum, this measurement can derive the Zodiacal brightness, testing models of the Zodiacal light based on morphology that are used to determine the extragalactic background light in absolute photometry measurements. The spectrometer is based on a simple high-resolution tipped filter placed in front of a compact camera with wide-field refractive optics to provide the large optical throughput and high sensitivity required for rocket-borne observations. We discuss the instrument requirements for an accurate measurement of the absolute Zodiacal light brightness, the measured laboratory characterization, and the instrument performance in flight.